This invention relates to a machine for sealing the upper ends of cups filled with a product such as a food product. The cups may, for example, be of the type used to hold yogurt, cottage cheese, sour cream, snack dips or the like.
A machine of this general type is disclosed in Shaw et al U.S. Pat. No. 4,736,568. In that machine, a web of heat-sealable material is advanced in overlying relation with a row of filled cups to a sealing station where both the web and a cup dwell momentarily. During the dwell period, a head at the sealing station advances downwardly and successively tamps a disc-like portion of the web downwardly into the upper end portion of the cup, seals the outer periphery of the disc-like portion to and around the upper lip of the cup and then severs the disc-like portion from the web so as to leave the cup sealed with a flexible membrane.
The Shaw et al patent contemplates that a plurality of individual sealing heads may be located at the sealing station and may be simultaneously operated in order to effect sealing of a group of cups at the same time. Each sealing head includes an individual actuator and each is moved downwardly through its full stroke whenever the actuator is operated.